Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751284AbdDBJ6v (ORCPT ); Sun, 2 Apr 2017 05:58:51 -0400 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:47784 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750947AbdDBJ6t (ORCPT ); Sun, 2 Apr 2017 05:58:49 -0400 Subject: Re: [PATCH v3] iio:adc: Driver for Linear Technology LTC2497 ADC To: michael.hennerich@analog.com, lars@metafoo.de, knaack.h@gmx.de, pmeerw@pmeerw.net, robh+dt@kernel.org, mark.rutland@arm.com References: <1490780578-2468-1-git-send-email-michael.hennerich@analog.com> Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org From: Jonathan Cameron Message-ID: <85744766-15cf-23be-895d-8de48cf5a3ac@kernel.org> Date: Sun, 2 Apr 2017 10:58:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <1490780578-2468-1-git-send-email-michael.hennerich@analog.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11675 Lines: 393 On 29/03/17 10:42, michael.hennerich@analog.com wrote: > From: Michael Hennerich > > This patch adds support for the Analog Devices / Linear Technology > LTC2497 ADCs. The LTC2497 is a 16-channel (eight differential), > 16-bit, high precision, delta-sigma ADC with an automatic, differential, > input current cancellation front end and a 2-wire, I2C interface. > > Signed-off-by: Michael Hennerich oops. Picked up the wrong version (thanks Lars). Dropped v2 and now applied v3. Sorry about that Jonathan > > --- > > Changes since v1: > > - remove confusing kconfig help text > - use proper defines > - add descriptive comment > - fix removal order > - add poper commit mssage > > Changes since v2: > > - Sort includes > - Use BIT() defines > - Avoid transfer buffers on the stack > - use msleep_interruptible() > - Fix documentation s/Should/Must/g > --- > .../devicetree/bindings/iio/adc/ltc2497.txt | 13 + > MAINTAINERS | 1 + > drivers/iio/adc/Kconfig | 10 + > drivers/iio/adc/Makefile | 1 + > drivers/iio/adc/ltc2497.c | 279 +++++++++++++++++++++ > 5 files changed, 304 insertions(+) > create mode 100644 Documentation/devicetree/bindings/iio/adc/ltc2497.txt > create mode 100644 drivers/iio/adc/ltc2497.c > > diff --git a/Documentation/devicetree/bindings/iio/adc/ltc2497.txt b/Documentation/devicetree/bindings/iio/adc/ltc2497.txt > new file mode 100644 > index 0000000..a237ed9 > --- /dev/null > +++ b/Documentation/devicetree/bindings/iio/adc/ltc2497.txt > @@ -0,0 +1,13 @@ > +* Linear Technology / Analog Devices LTC2497 ADC > + > +Required properties: > + - compatible: Must be "lltc,ltc2497" > + - reg: Must contain the ADC I2C address > + - vref-supply: The regulator supply for ADC reference voltage > + > +Example: > + ltc2497: adc@76 { > + compatible = "lltc,ltc2497"; > + reg = <0x76>; > + vref-supply = <<c2497_reg>; > + }; > diff --git a/MAINTAINERS b/MAINTAINERS > index a7d6f9a..173043c 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -813,6 +813,7 @@ W: http://wiki.analog.com/ > W: http://ez.analog.com/community/linux-device-drivers > S: Supported > F: drivers/iio/*/ad* > +F: drivers/iio/adc/ltc2497* > X: drivers/iio/*/adjd* > F: drivers/staging/iio/*/ad* > F: drivers/staging/iio/trigger/iio-trig-bfin-timer.c > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > index 2268a6f..acc115b 100644 > --- a/drivers/iio/adc/Kconfig > +++ b/drivers/iio/adc/Kconfig > @@ -326,6 +326,16 @@ config LTC2485 > To compile this driver as a module, choose M here: the module will be > called ltc2485. > > +config LTC2497 > + tristate "Linear Technology LTC2497 ADC driver" > + depends on I2C > + help > + Say yes here to build support for Linear Technology LTC2497 > + 16-Bit 8-/16-Channel Delta Sigma ADC. > + > + To compile this driver as a module, choose M here: the module will be > + called ltc2497. > + > config MAX1027 > tristate "Maxim max1027 ADC driver" > depends on SPI > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile > index 73dbe39..9d626b5 100644 > --- a/drivers/iio/adc/Makefile > +++ b/drivers/iio/adc/Makefile > @@ -32,6 +32,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o > obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o > obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o > obj-$(CONFIG_LTC2485) += ltc2485.o > +obj-$(CONFIG_LTC2497) += ltc2497.o > obj-$(CONFIG_MAX1027) += max1027.o > obj-$(CONFIG_MAX11100) += max11100.o > obj-$(CONFIG_MAX1363) += max1363.o > diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c > new file mode 100644 > index 0000000..2691b10 > --- /dev/null > +++ b/drivers/iio/adc/ltc2497.c > @@ -0,0 +1,279 @@ > +/* > + * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC > + * > + * Copyright (C) 2017 Analog Devices Inc. > + * > + * Licensed under the GPL-2. > + * > + * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define LTC2497_ENABLE 0xA0 > +#define LTC2497_SGL BIT(4) > +#define LTC2497_DIFF 0 > +#define LTC2497_SIGN BIT(3) > +#define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE > +#define LTC2497_CONVERSION_TIME_MS 150ULL > + > +struct ltc2497_st { > + struct i2c_client *client; > + struct regulator *ref; > + ktime_t time_prev; > + u8 addr_prev; > + /* > + * DMA (thus cache coherency maintenance) requires the > + * transfer buffers to live in their own cache lines. > + */ > + __be32 buf ____cacheline_aligned; > +}; > + > +static int ltc2497_wait_conv(struct ltc2497_st *st) > +{ > + s64 time_elapsed; > + > + time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev); > + > + if (time_elapsed < LTC2497_CONVERSION_TIME_MS) { > + /* delay if conversion time not passed > + * since last read or write > + */ > + if (msleep_interruptible( > + LTC2497_CONVERSION_TIME_MS - time_elapsed)) > + return -ERESTARTSYS; > + > + return 0; > + } > + > + if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) { > + /* We're in automatic mode - > + * so the last reading is stil not outdated > + */ > + return 0; > + } > + > + return 1; > +} > + > +static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val) > +{ > + struct i2c_client *client = st->client; > + int ret; > + > + ret = ltc2497_wait_conv(st); > + if (ret < 0) > + return ret; > + > + if (ret || st->addr_prev != address) { > + ret = i2c_smbus_write_byte(st->client, > + LTC2497_ENABLE | address); > + if (ret < 0) > + return ret; > + st->addr_prev = address; > + if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS)) > + return -ERESTARTSYS; > + } > + ret = i2c_master_recv(client, (char *)&st->buf, 3); > + if (ret < 0) { > + dev_err(&client->dev, "i2c_master_recv failed\n"); > + return ret; > + } > + st->time_prev = ktime_get(); > + > + /* convert and shift the result, > + * and finally convert from offset binary to signed integer > + */ > + *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17); > + > + return ret; > +} > + > +static int ltc2497_read_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + int *val, int *val2, long mask) > +{ > + struct ltc2497_st *st = iio_priv(indio_dev); > + int ret; > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + mutex_lock(&indio_dev->mlock); > + ret = ltc2497_read(st, chan->address, val); > + mutex_unlock(&indio_dev->mlock); > + if (ret < 0) > + return ret; > + > + return IIO_VAL_INT; > + > + case IIO_CHAN_INFO_SCALE: > + ret = regulator_get_voltage(st->ref); > + if (ret < 0) > + return ret; > + > + *val = ret / 1000; > + *val2 = 17; > + > + return IIO_VAL_FRACTIONAL_LOG2; > + > + default: > + return -EINVAL; > + } > +} > + > +#define LTC2497_CHAN(_chan, _addr) { \ > + .type = IIO_VOLTAGE, \ > + .indexed = 1, \ > + .channel = (_chan), \ > + .address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \ > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ > +} > + > +#define LTC2497_CHAN_DIFF(_chan, _addr) { \ > + .type = IIO_VOLTAGE, \ > + .indexed = 1, \ > + .channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \ > + .channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\ > + .address = (_addr | _chan), \ > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ > + .differential = 1, \ > +} > + > +static const struct iio_chan_spec ltc2497_channel[] = { > + LTC2497_CHAN(0, LTC2497_SGL), > + LTC2497_CHAN(1, LTC2497_SGL), > + LTC2497_CHAN(2, LTC2497_SGL), > + LTC2497_CHAN(3, LTC2497_SGL), > + LTC2497_CHAN(4, LTC2497_SGL), > + LTC2497_CHAN(5, LTC2497_SGL), > + LTC2497_CHAN(6, LTC2497_SGL), > + LTC2497_CHAN(7, LTC2497_SGL), > + LTC2497_CHAN(8, LTC2497_SGL), > + LTC2497_CHAN(9, LTC2497_SGL), > + LTC2497_CHAN(10, LTC2497_SGL), > + LTC2497_CHAN(11, LTC2497_SGL), > + LTC2497_CHAN(12, LTC2497_SGL), > + LTC2497_CHAN(13, LTC2497_SGL), > + LTC2497_CHAN(14, LTC2497_SGL), > + LTC2497_CHAN(15, LTC2497_SGL), > + LTC2497_CHAN_DIFF(0, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(1, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(2, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(3, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(4, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(5, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(6, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(7, LTC2497_DIFF), > + LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN), > + LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN), > + LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN), > + LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN), > + LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN), > + LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN), > + LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN), > + LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN), > +}; > + > +static const struct iio_info ltc2497_info = { > + .read_raw = ltc2497_read_raw, > + .driver_module = THIS_MODULE, > +}; > + > +static int ltc2497_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + struct iio_dev *indio_dev; > + struct ltc2497_st *st; > + int ret; > + > + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | > + I2C_FUNC_SMBUS_WRITE_BYTE)) > + return -EOPNOTSUPP; > + > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st)); > + if (!indio_dev) > + return -ENOMEM; > + > + st = iio_priv(indio_dev); > + i2c_set_clientdata(client, indio_dev); > + st->client = client; > + > + indio_dev->dev.parent = &client->dev; > + indio_dev->name = id->name; > + indio_dev->info = <c2497_info; > + indio_dev->modes = INDIO_DIRECT_MODE; > + indio_dev->channels = ltc2497_channel; > + indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel); > + > + st->ref = devm_regulator_get(&client->dev, "vref"); > + if (IS_ERR(st->ref)) > + return PTR_ERR(st->ref); > + > + ret = regulator_enable(st->ref); > + if (ret < 0) > + return ret; > + > + ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT); > + if (ret < 0) > + goto err_regulator_disable; > + > + st->addr_prev = LTC2497_CONFIG_DEFAULT; > + st->time_prev = ktime_get(); > + > + ret = iio_device_register(indio_dev); > + if (ret < 0) > + goto err_regulator_disable; > + > + return 0; > + > +err_regulator_disable: > + regulator_disable(st->ref); > + > + return ret; > +} > + > +static int ltc2497_remove(struct i2c_client *client) > +{ > + struct iio_dev *indio_dev = i2c_get_clientdata(client); > + struct ltc2497_st *st = iio_priv(indio_dev); > + > + iio_device_unregister(indio_dev); > + regulator_disable(st->ref); > + > + return 0; > +} > + > +static const struct i2c_device_id ltc2497_id[] = { > + { "ltc2497", 0 }, > + { } > +}; > +MODULE_DEVICE_TABLE(i2c, ltc2497_id); > + > +static const struct of_device_id ltc2497_of_match[] = { > + { .compatible = "lltc,ltc2497", }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, ltc2497_of_match); > + > +static struct i2c_driver ltc2497_driver = { > + .driver = { > + .name = "ltc2497", > + .of_match_table = of_match_ptr(ltc2497_of_match), > + }, > + .probe = ltc2497_probe, > + .remove = ltc2497_remove, > + .id_table = ltc2497_id, > +}; > +module_i2c_driver(ltc2497_driver); > + > +MODULE_AUTHOR("Michael Hennerich "); > +MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver"); > +MODULE_LICENSE("GPL v2"); >